JP2003508972A - High-performance line card for lifeline packet voice telephony and CPE for packetization - Google Patents

Abstract

(57) A voice and data communication system (60) wherein a line card (66) digitizes and packetizes voice communication signals in the event of a failure of a customer premises equipment (CPE) (62). The system includes a line card (66) that couples the CPE (62) with the networks (12 and 32). Further, the present invention provides a system capable of sending voice signals to one or both of a voice network (12) and a data network (32).

Description

Detailed Description of the Invention

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority from Canadian Patent Application No. 2,281,356, filed Sep. 1, 1999.

BACKGROUND OF THE INVENTION The present invention relates generally to the field of Digital Subscriber Lines (DSL), and more particularly to packetized voice access systems.

Telephone services are typically provided by the Public Switched Telephone Network (PSTN). P
STNs are used for various transport media and transport formats (P
STN transport network) and includes a plurality of telephone exchanges connected by twisted pair loop wires to telephone terminals at the subscriber's premises.

FIG. 1 illustrates a conventional circuit switched telephone network, generally designated by the numeral 10.
In this example, PSTN transport network 12 interconnects with telephone switch 14. The switch interfaces with individual twisted pair loops 18 and telephone terminals 20 via POTS line cards 16. In the case of a typical home telephone service, the POTS line card 16 has some functions necessary for operating the telephone terminal 20 connected to the subscriber's home. These functions are typically collectively referred to as BORSCHT and typically include, but are not limited to: Battery: Provides power. Overvoltage: Protects the line card from environmentally generated overvoltage. Ringing signal: A signal for activating a telephone terminal receiver is supplied. Surveillance: Detects whether the subscriber's telephone receiver handset is on or off. Encoding: Converting an analog loop signal into a digital representation. Hybrid: Separates the received signal from the transmitted signal. Termination: Terminates the loop with the required standard electrical impedance on the line card.

Although the implementation details are different, the B, O, R, S, T functions are typically located in the analog front end 22 and the C, H, T functions are located in the voice engine 24. . The line card 16 supplies power from the uninterruptible power supply 26 to the telephone terminal 20.
The power supply 26 is physically located within the telephone central office and is referred to as the central office (CO) battery. The CO battery plant is designed and sized to power conventional telephone terminals 20, even in the event of a total blackout. Thus, telephone services are characterized by a high degree of availability, or class of service called "lifeline" POTS. In general, the line card 16 can supply the twisted pair loop 18 and the telephone 20 with currents up to 30 mA at 48V. However, the exact current value depends on the combined electrical resistance of the twisted pair loop 18 and the telephone terminal 20. Strict current limit depends on the implementation, 20 mA to 35 mA
It is in the mA range.

With the explosive growth of data communications, multi-service data networks (MSDN) have evolved and now have more bandwidth and more rapid growth than PSTN transport networks. There is. Data communication networks have been developed that can more easily support protocols and network elements that route and switch large collections of bits known as packets or cells. Basically, each packet / cell can be independently routed or switched by a device called a router to a different destination based on the destination address stored in each packet or cell. This is called packet switched networking. If the packet stream contains a digital representation of a voice conversation, the routing of these packets will be similar in function to traditional circuit switched telephone switching. Note that the term voice is used generically and its definition can be extended to include other analog transmissions such as fax and conventional modems. In the following description, it should be understood that a packet and a cell are similar entities. Unless otherwise indicated, packets and cells are interchangeable and can be used individually without limiting the generality of the description. V
oIP (Voice over IP) and VoATM (Voice over IP)
The term ATM) can be treated similarly.

FIG. 2 illustrates a network configuration for interconnecting an MSDN to a conventional telephone using voice packetization technology, a packet switched voice access network 30.
Indicates. Multi-service data network 32 interconnects packets / cells between various Digital Subscriber Loop Access Multiplexers (DSLAMs) 34, which multiplex data streams from multiple DSL line cards 36. Route. Each DSL line card 36 is a DSL customer premises equipment (CPE)
Interface and communicate with the DSL CPE via twisted pair loop 18. The DSL CPE may be stand-alone and may be connected to a source of packet / cell data, such as a computer (not shown), or a DS inside the computer.
It may be an L network interface card (DSL NIC) (not shown), or it may be a CPE, here a CPE 38 for voice packetization. DS
The L-line card 36 communicates to the twisted pair loop 18, which is commonly used to carry POTS signals, using any of several methods of applying a signal representative of a digital bit stream. You can These methods include ADS
L (asymmetrical DSL), SDSL (symmetrical DSL), HDSL (high speed DSL), VD
SL (Ultra High Speed DSL), ISDN (Service Integrated Digital Communication Network), MVL (M
multiple virtual lines) or CAP
(Carrierless Amplitude / Phase: Carrierless amplitude /
There are, but are not limited to, methods or services commonly referred to as "phases".

The voice packetizing CPE 38 converts the analog signal from the ordinary telephone terminal 20 into
It is converted into voice packets or cells suitable for carrying over the twisted pair loop 18 from the subscriber's home in the form of DSL signals. To operate the conventional telephone terminal 20, the voice packetizing CPE 38 included most of the functionality associated with the conventional telephone switched POTS line card 16 in the voice engine 42 and the analog front end 44. The specific differences from the corresponding POTS line card block are that it encodes into a 16-bit linear digital representation instead of the μ-conversion rule or the A-conversion rule, it supplies the telephone terminal with 24V power instead of 48V, This may include reduced robustness against line overvoltage. Such differences do not affect the nature or importance of the functions described below. VoIP (Voice over)
Internet Protocol) or VoATM (Voice ov)
er Asynchronous Transfer Mode) engine 4
6 is the bit of the digitized audio stream received from the audio engine 42.
It may also include rate reducing circuitry and algorithms. VoIP / Vo
The ATM engine 46 may also include echo cancellation functionality to process the reduced bit rate stream into packets or cells to reduce the subjective audible effects of delays caused by encoding and packetizing operations. These functions are usually described in ITU Recommendation H.264. 323, G.I. Implements a set of protocols that can include implementations of 168 or similar standards, or similar algorithms. VoI
The packet / cell stream generated from the P / VoATM engine 46 is D
Transmission and reception are performed with the DSLAM 34 using the SL modem 40. The DSL modem 40 complies with ITU Recommendation G. 992.1 (“Full Rate ADSL”) or G.I. 9
Any of a variety of digital subscriber loop standards can be implemented, such as 92.2 (“ADSL Lite”).

The circuitry contained within the voice packetizing CPE 38 requires more power than can normally be provided by the line card 36 and is therefore typically powered by a power source 48 that draws power from local commercial AC power. When commercial AC power is cut off due to local power outage, voice packetization CP is used until commercial AC power is restored.
Communication using E is not possible. This is a problem for subscribers who are accustomed to telephone services that are available during power outages, especially in the event of life and safety threats. Uninterruptible AC power supplies (UPS) are commercially available that can supply AC power for a short time in the event of local power failure of commercial AC power. However, the drawbacks of local UPS are that they are expensive to purchase, have limited time to power such equipment, and require regular maintenance to ensure that they operate in the event of a power outage. Is there.

Moreover, in conventional packet-based networks, to implement lifeline packet voice services, up to three separate devices, namely DSLA
M, a POTS access device such as a digital loop concentrator, and a gateway are required. The gateway is one item of network equipment, PSTN
And MSDN to convert and mediate voice signals, signaling signals, and protocols. The need for three separate devices adds to the complexity of the overall network and equipment, and to service provisioning and maintenance.

What is needed is a mechanism that eliminates or mitigates at least some of the above drawbacks.

According to the present invention, there is provided a voice and data communication system in which a line card digitizes and packetizes a voice communication signal even when a CPE (customer premises equipment) is broken. The system comprises a line card that couples the network with the CPE. This line card consists of an analog front end that connects the line card to the CPE, a digitizer that digitizes the received voice signal, a packetizer that packetizes the digitized voice signal, and a modem that transmits the packet. A system interface for coupling the line card to at least one network.

Further, the present invention provides a system capable of sending voice signals to either or both a voice network (ie PSTN) and a data network (ie MSDN). The system consists of an analog front end that couples a line card to a telephone, a digitizer that digitizes the received voice signal, a packetizer that packetizes the digitized voice signal, and a data signal that digitizes the signal. It includes a line card that includes a modem for transmitting to the network, a system interface for coupling the line card to voice and data networks, and a controller for controlling the destination of the voice signal.

The present invention will be better understood with reference to the following description of specific embodiments and the accompanying drawings.

[0015]     (Description of specific embodiments)   For convenience, the same structure in the drawings is represented by the same numeral.

FIG. 3 illustrates a lifeline packet based voice access system, generally designated 60, according to the present invention. The system 60 can provide lifeline-class services for packet voice calls using the Lifeline Packetization Voice (LPV) CPE 62 described below or the conventional analog telephone terminal 20.

The LPV CPE 62 includes a functional block with a conventional voice packetizing CPE 38, as previously described and shown in FIG. Specifically, the DSL modem 40,
It includes a VoIP or VoATM engine 46, a voice engine 42, an analog front end 44, and a power supply 48. In addition, the LPV CPE may include an optional POTS splitter 78, which allows telephone terminal 20 to be connected to twisted pair 18 via relay 80. The relay 80 has a common contact connected to the telephone terminal 20 and a normally closed contact connected to the POTS splitter 78. The relay is activated by a DSL sync detect signal 76 from the DSL modem 40 in the voice packetizing CPE.

Under normal conditions, ie when there is commercial AC power to the lifeline packetizing CPE and the DSL modem is synchronized to the valid DSL signal on the twisted pair loop, the DSL sync detect signal is Asserted and energizes relay 80. When the relay 80 is energized, the common contact is connected to the relay's normally open contact. Therefore, the telephone terminal 20 is connected to the voice packetizing CPE 38, whereby a digital packet / cell stream in the form of a DSL signal is delivered to the LPV line card 6.
6 is sent to the MSDN 32 through the DSL modem 35, and voice communication can be performed.

However, there is a local power failure to the lifeline packetization CPE 62, or the DSL modem 40 component of the voice packetization CPE 38 is enabled D
If the SL signal is not detected, the DSL sync detection signal 75 disappears and the relay 80 is deactivated. Accordingly, the telephone terminal 20 is connected to the twisted pair loop 18 via the normally closed contacts of the relay 80 and the POTS splitter 78. In this state,
The telephone terminal is directly connected to the twisted pair (via the POTS splitter 78) and from the CO battery via the Broadband Analog Front End (BAFE) 72 on the Lifeline Packet Voice Line Card (LPVLC) 68. Power is supplied. Voice communication is performed through the voice engine 24 on the line card 66 and the VoIP / VoATM engine 46 in the voice line card system for packetization.

A plurality of Lifeline Packet Voice Line Cards (LPVLC) 66 are contained within a suitable access device 68. The device 68 may be a digital loop carrier system, a voice-capable DSLAM, a data-capable digital telephone switch, or the like.

The lifeline packet voice line card 66 includes an analog telephone terminal and a DS.
It contains circuitry to interface with L-based CPE. The system interface 70 is a public switched telephone network (PSTN) 12 and multi-service
It contains circuitry that interfaces with a data network (MSDN) 32. The interfaces described here are conceptually the same as the respective interfaces shown in FIGS. 1 and 2. The voice engine 24 and the DSL modem 35 may be of the type shown in the respective blocks in FIGS.
Broadband analog front end 72 includes voice-only analog front end 22 of the POTS line card of FIG. 1 and D of the DSL line card of FIG.
It also has the function of the SL front end 37. Broadband front end 72 provides the B, O, R, S, and T functions needed to support both voice and DSL signals over the entire bandwidth, terminating impedance, drive level, linearity, And meet different requirements of DSL and POTS interface types for loop feeding.

The VoIP or VoATM engine 46 performs functions of the type previously described and shown in the voice packetizing CPE 38 of FIG. The engine 46 takes the digitized voice from the voice engine 24 and performs compression, packetization, and optionally echo cancellation. The resulting voice packets are sent to the system interface 70 where they are merged with the packet / cell stream from the DSL modem block 35. This merge function may be implemented in LPVLC or elsewhere in access device 68. This merging is controlled by the merge controller 74 and produces a merge signal. The merge signal 75 is sent to the voice engine 24, the VoIP engine 46, and the system interface 7.
Sent to block 0. The merge controller 74 can be configured to operate in multiple modes described below. If the merge control signal 75 is continuously asserted, the system is in voice mode for packetization and the line card 66 is packetizing the voice signal while powering the conventional voice terminal 20 and the resulting packet stream. Can be sent to MSDN. If the merge control signal 75 is continuously canceled, the system will be in the POTS-only mode or the packetizing CPE-only mode and the line card 66 will not be able to packetize the voice signal. However, the merge control signal 75 can also be responsive to the DSL Synch Detect signal 76 generated by the DSL modem 35 whenever a valid DSL signal originating from the subscriber CPE is detected. According to the present invention, when the CPE is not functioning at all, probably due to a utility power outage, the line card powers the conventional telephone terminal while packetizing the voice signal and sending the resulting packet stream to the MSDN. .

Therefore, the lifeline packet voice line card 66 of the present invention can execute the function of the conventional POTS line card shown in FIG. 1 or the function of the DSL line card shown in FIG. . When operating as a DSL line card 36, the lifeline packet voice line card 66 can be part of a conventionally defined VoIP / VoATM system that performs voice packetization at the CPE. The access device 68 in such a system does not process or alter the contents of the packets or cells in the VoIP or VoATM stream, but simply transports the VoIP or VoATM stream appropriately from the subscriber to the MSDN 32.

The lifeline packet voice line card 66 can also operate as a packetizing voice line card. In this mode, LPV line card 66
Provides an interface to conventional telephone terminals 20 via BAFE 72 and voice engine 24. Therefore, in the event of a power failure at the subscriber's house, the telephone terminal will continue to use the central office (CO) battery (not shown) via the BAFE 72 as before.
Powered by, and still capable of transmitting voice signals to the line card 66.
The voice engine 24 on the line card 66 digitizes the voice signal and then VoI
Packetized by the P / VoATM engine 46. The obtained packet / cell stream is sent from the system interface 70 to the MSDN 32. Since the telephone terminal is powered by the CO and the voice signal is delivered to the MSDN 32 as a packet / cell stream, the net result is a packet voice communication capability with lifeline class services.

Up to this point, this system necessarily powers the telephone terminal and communicates with it,
And packetizing voice has only been described as if it were a mutually exclusive function with DSL communication. However, if the system definition is P on the same loop,
It can also be extended to provide DSL communication at the same time as the OTS interface. The ability to do DSL and POTS simultaneously on a single loop, for example ADSL
However, it is not necessarily possible with any other type of DSL modem or modulation scheme.

Referring again to FIG. 3, telephone terminal 20 and DSL modem 82 are in communication with access device 68 over POTS splitter 84 on the same loop 18. In some circumstances splitter 84 may be optional. Usually DSL
The data from the CPE 82 and the voice signal from the telephone 20 will communicate on the same loop 18. These signals are filtered by BAFE 72, after which the audio signals are sent to PSTN 12 via audio engine 24 and system interface 70. The data signal is sent to the DSL modem 35, demodulated by it, and the resulting data packet / cell stream is sent to the MSDN 32 via the system interface 70. Thus, voice and data processing can be done simultaneously on a single line card.

Alternatively, after the voice engine 24 digitizes the voice signal, VoIP / Vo
The ATM engine 46 can be used to packetize digitized voice signals,
The system interface 70 can merge voice packets with data packets from the DSL modem 35. The merged packet stream is sent on MSDN. System interface 70 to simultaneously provide lifeline packet voice and data communication capabilities to MSDN over DSL.
Includes the function of multiplexing packets or cells. With this multiplexer, V
The voice packet or cell stream from the oIP / VoATM engine 46 will now be able to be merged with the packet or cell stream from the DSL modem 35. As mentioned previously, the merge function can be implemented within the LPVLC or elsewhere in the access device 68. Also, with the multiplexer,
It will also be possible to distribute the voice packet stream or cell stream from the MSDN so that the appropriate streams are each VoIP / Vo.
It is sent to the ATM engine 46 and the DSL modem 35.

Therefore, the lifeline packet voice line card 66 is
4 to the PSTN 12 or to the MSDN 32 via the VoIP / VoATM engine 46, or simultaneously to both. For each call, a decision can be made as to where to send the voice packet stream. The ability to redirect calls exists at all times and for so many reasons, for example in the event of a power failure or network connection failure. Therefore, the line card 66 is a PSTN or M
It has the ability to rapidly change the path taken over a voice connection, via either SDN.

As a result of the architecture used, the system is capable of high quality speech coding referred to as intelligent packet speech. With traditional system architectures, it was difficult to increase the transport bandwidth between the voice coder and the packetizer, so it was not possible to always provide high-performance packet voice,
It could be a physically separate and geographically dispersed device. The architecture of this embodiment of the present invention uses a voice coder 24 and a packetizer 46 on the same card so that intelligent packet voice can be implemented.

Intelligent packet voice forms an alternative high quality encoding function within voice engine 24 and VoIP / VoATM engine 46, optionally with 300-3400 Hz bandwidth of normal toll quality voice. It is realized by combining with the function of encoding the audio frequency outside the. Alternatively, the functionality may be implemented within the corresponding components of CPE 62.

The high-performance packet voice is a normal μ conversion rule or A
The non-linearity of transform law coding is beneficial in applications where the effectiveness of algorithms that process coded speech or speech band signals is reduced. Examples of alternative coders for voice engines include 16-bit linear coders, faster than normal sampling rates, 1
There are coders that are 6-bit linear coders and have faster sampling rates. The loss of effectiveness is usually, but not exclusively, due to non-linear coding, which degrades the coding quality of the desired signal in the presence of stronger, unwanted signals.

Examples of alternative coders for the VoIP / VoATM engine include studio or CD
There is a perceptual coder defined for quality speech. Alternative high quality coders typically provide faster packet / cell rates from the VoIP / VoATM engine.

Although the present invention has been described in terms of certain specific embodiments, those skilled in the art can make various modifications thereof without departing from the spirit and scope of the invention as outlined in the claims appended hereto. Would be obvious.

[Brief description of drawings]

[Figure 1]   FIG. 1 is a block diagram of an interface of a conventional circuit switched telephone network.

[Fig. 2]   FIG. 1 is a block diagram of a conventional packet voice access system.

FIG. 3 is a block diagram of a lifeline packetized voice access system according to the present invention.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, C H, CN, CR, CU, CZ, DE, DK, DM, DZ , EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, K G, KP, KR, KZ, LC, LK, LR, LS, LT , LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, S E, SG, SI, SK, SL, TJ, TM, TR, TT , TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Boocock, Jonathan             Canada 0K 3M 0ONTA             Rio Woodlawn Bayview Dry             B 742 are are are number 1 (72) Inventors Dekzukii and Andrew             Canada Country 0 Kei 2 Kei 7 Onta             Rio Ottawa Highlands Avenue             732 (72) Inventor Weirich, Andreas             Canada, K2S, 1J7, Onta             Rio Stittsville Basford             Crescent 15 (72) Inventor Feeley, Mark             Canada, K2K2K2A1ONTA             Rio Kanata Marchbrook Sark             Le 26 F-term (reference) 5K030 HB01 JA05 JA09 JL08 JT01                       KA23                 5K051 AA08 BB01 BB02 CC01 CC02                       DD01 DD11 EE01 EE07 FF07                       HH01 HH26 HH27                 5K101 KK02 LL01 LL02 LL03 MM01                       NN03 NN07 NN14 QQ11 SS07

Claims (13)

[Claims] 1. A voice and data communication system comprising a customer premises equipment (CPE) element and a line card for transporting communication signals between a subscriber and a network, said line card via a transmission medium. An analog front end for coupling the line card to the CPE, a digitizer for digitizing the received voice signal, a packetizer for packetizing the digitized voice signal, and transmitting voice and data packets to the CPE And a data communication system interface for coupling the line card to at least one network, wherein the line card digitizes and packetizes the voice signal when the CPE fails. 2. The CPE digitizer for digitizing a received voice signal, a packetizer for packetizing the digitized voice signal, a modem for transmitting voice packets, and a POTS (packetizing data communication system). An existing ordinary telephone data communication system), and a data exchange system for diverting to a terminal. 3. The data communication system according to claim 2, wherein the exchange is a relay that switches between the packetizer and the POTS data communication system. 4. The data communication system according to claim 3, wherein the position of the exchange is determined by a signal, and the signal indicates a connection status between the CPE and the line card. 5. The data communication system of claim 1, wherein the modem is a digital subscriber line (DSL) modem. 6. The line card of claim 2, wherein when the CPE fails to packetize the voice signal, the line card does so and the CPE digitizer and packetizer is bypassed. Data communication system. 7. The data communication system according to claim 2, wherein the failure is a power failure at the location of the subscriber. 8. The data communication system of claim 2, wherein the failure is the inability to synchronize a DSL modem on the CPE with a DSL modem on the line card. 9. The data communication system according to claim 2, wherein the digitizer performs high quality speech coding. 10. The data communication system according to claim 2, wherein the packetizer performs high quality speech coding. 11. A system comprising a line card for receiving a voice signal from a telephone and providing a voice signal for transmission, said line card comprising an analog front end for coupling the line card to said telephone. A digitizer for digitizing the received voice signal, a packetizer for packetizing the digitized voice signal, a modem for receiving voice packets from a CPE and transmitting the voice packets to a data network, and a line card for voice A system comprising: a network and a data communication system interface coupled to the data network; and a controller controlling a destination of the voice signal, the system capable of supplying the voice signal to the voice network and the data network. 12. The line card operates to receive a data signal on the same loop as the voice signal, the analog front end separates the data signal from the voice signal, and the modem controls the data signal. The system of claim 11, transmitting a data signal to the data network. 13. The system of claim 11, wherein the modem is a DSL modem.